Method and apparatus for reserving resources of one or more multiple access communication channels
DC CAFCFirst Claim
1. A method for enabling a station to communicate via a shared medium of a multiple access network comprising the steps of:
- (a) transmitting a reservation request bitstream containing a request to reserve one or more slots of an upstream payload channel on an upstream control channel, (b) receiving a plurality of bitstreams from a downstream channel, including at least one bitstream containing an indication of one or more slots of said upstream payload channel assigned to said station for transmitting bitstreams, (c) transmitting payload bitstreams on said upstream payload channel, only at said assigned slots of said upstream payload channel, and (d) switching between transmitting said reservation request bitstreams and the payload bistreams, such that said reservation request and payload bitstreams are sequentially transmitted, wherein said upstream control channel, said upstream payload channel and said downstream channel each have a mutually different frequency band.
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Litigations
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Accused Products
Abstract
A method and system are disclosed for enabling point-to-point and multicast communication in a multiple access network using three types of communication channels, namely, one or more upstream payload channels, one or more upstream control channels and one or more downstream channels. Each channel illustratively is divided into slots or mini-slots. Each upstream payload channel is assigned for carrying upstream directed payload bitstreams from stations to a central controller. The central controller has an independent receiver for each upstream channel for simultaneous reception of control and payload bitstreams. Each station has at least one frequency agile programmable transmitter for sequential transmission of control and payload bitstreams or separate upstream control and payload channel transmitters, respectively, for simultaneous transmission of control and payload bitstreams. Each upstream control channel is assigned for carrying upstream directed control bitstreams, such as reservation request bitstreams requesting reservation of time slots of the upstream payload channel, from the stations to the central controller. At least one downstream channel is assigned for carrying at least downstream directed control bitstreams, such as bitstreams containing network configuration acknowledgments, collision, status of reservation request, and also containing indications of assigned slots in the upstream payload channel, from the central controller to the stations. The downstream channel may also illustratively carry payload bitstreams.
235 Citations
38 Claims
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1. A method for enabling a station to communicate via a shared medium of a multiple access network comprising the steps of:
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(a) transmitting a reservation request bitstream containing a request to reserve one or more slots of an upstream payload channel on an upstream control channel, (b) receiving a plurality of bitstreams from a downstream channel, including at least one bitstream containing an indication of one or more slots of said upstream payload channel assigned to said station for transmitting bitstreams, (c) transmitting payload bitstreams on said upstream payload channel, only at said assigned slots of said upstream payload channel, and (d) switching between transmitting said reservation request bitstreams and the payload bistreams, such that said reservation request and payload bitstreams are sequentially transmitted, wherein said upstream control channel, said upstream payload channel and said downstream channel each have a mutually different frequency band. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
(e) after beginning to perform step (a), receiving from said downstream channel a bitstream indicating that a collision occurred in said upstream control channel in performing said step (a), and (f) in response, retransmitting said reservation request bitstream.
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3. The method of claim 1 further comprising the steps of:
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(e) prior to step (a), waiting until a bitstream is received from said downstream channel indicating the identity of an available group of one or more reservation slots in said upstream control channel, and (f) if data is available for transmission from said station, randomly determining, based on said indicated available group of reservation slots, whether or not to perform step (a), but only during one of said reservation slots of said indicated group of reservation slots.
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4. The method of claim 1 further comprising the steps of:
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(e) after performing step (a) but before step (b), setting an acknowledgment timer, and (f) in response to said acknowledgment timer expiring before receiving a bitstream containing an acknowledgment from said downstream channel, repeating step (a).
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5. The method of claim 4 further comprising the steps of:
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(g) after performing step (d), but before performing step (f), receiving a bitstream from said downstream channel containing an acknowledgment of receipt of said reservation request but also indicating that no slots in said upstream payload channel are available for allocation, and (h) refraining from repeating step (a) in said step (f).
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6. The method of claim 1 further comprising the step of:
(e) receiving from said downstream channel a payload bitstream containing a communicated message originating from another station in said multiple access network.
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7. The method of claim 1 wherein each of said bitstreams received from said downstream channel are organized into MPEG-2 transport packets.
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8. The method of claim 1 wherein said multiple access network is a cable network, said station is a subscriber station and said shared medium includes cabling.
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9. The method of claim 1 wherein said multiple access network is a wireless network, said station is a communication unit and said shared medium is the air.
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10. The method of claim 1 wherein said multiple access network is a satellite network, said station is an earth station and said shared medium comprises the air and space.
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11. The method of claim 1 wherein said downstream channel is received by a plurality of stations via said shared medium.
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12. The method of claim 1 wherein said upstream control channel and said upstream payload channel are multiple access channels.
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13. The method of claim 1 wherein first and second modulation techniques are used for said upstream control channel and said upstream payload channel, respectively, said first modulation technique optimizing the robustness of said upstream control channel without degrading the robustness or utilization of said upstream payload channel.
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14. The method of claim 1 wherein in step (a), said upstream control channel on which said bitstream containing said request is transmitted is one of plural upstream control channels.
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15. The method of claim 1 wherein in step (b), said downstream channel on which said bitstream containing said indication is received is one of plural downstream channels.
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16. The method of claim 1 wherein in step (c), said upstream payload channel on which said bitstream is transmitted is one of plural upstream payload channels.
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17. The method of claim 1 wherein prior to step (a), further comprising the step receiving a bitstream indicating an identity of said multiple access network from said downstream channel, wherein said identity of said network includes at least an identity of said downstream and upstream channels.
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18. In a central controller of a multiple access network, a method for enabling communication of bitstreams from a station via a shared medium of the network comprising the steps of:
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(a) receiving from an upstream control channel, a reservation request bitstream, requesting reservation of slots for a particular station, (b) transmitting on a downstream channel, a bitstream indicating one or more slots assigned to said particular station, and (c) receiving a bitstream from one or more of said assign slots of an upstream payload channel, wherein the received reservation request and payload bitstreams are transmitted from each said station by switching between said upstream control and upstream payload channels, and wherein said upstream control channel, said upstream payload channel and said downstream channel each have a mutally different frequency band. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
(d) detecting a collision during said step (a), and (e) in response to said collision, transmitting a bitstream in said download channel including a notification to each station that a collision occurred at a particular reservation request slot as indicated by at least one of a network identifier, an upstream control channel identifier and a reservation request mini-slot identifier.
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20. The method of claim 18 further comprising the steps of:
(d) transmitting on said downstream channel a bitstream including an indication of the occurrence of a group of one or more available slots on said upstream control channel.
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21. The method of claim 18 further comprising the steps of:
(d) after step (a) but before step (b), in response to an absence of available slots in said upstream payload channel, transmitting a bitstream on said downstream channel including an acknowledgment of receipt of said reservation request from said particular station but also including an indication that no slots of said upstream payload channel are currently available for allocation.
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22. The method of claim 18 further comprising the steps of:
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(d) receiving a payload bitstream from said upstream payload channel originating from a first station and destined to a second station, and (e) transmitting said payload bitstream on said downstream channel.
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23. The method of claim 18 wherein said upstream control channel and said upstream payload channel are multiple access channels.
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24. The method of claim 18 wherein said downstream channel is received by a plurality of stations via said shared medium.
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25. The method of claim 18 wherein in step (b), each of the assigned slots being indicated by at least one of a network identifier, a station identifier, an upstream payload channel identifier and a mini-slot identifier.
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26. The method of claim 20 wherein in step (d), each of said available slots being indicated by at least one of a network identifier, a station identifier, an upstream control channel identifier and a mini-slot identifier.
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27. A method for communicating in a multiple access network comprising a central controller, a station and a shared medium for carrying signals between said central controller and said station, comprising the steps of:
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(a) switching between transmitting payload bitstreams from a station to the central controller on an upstream payload channel and reservation request bitstreams from the station to the central controller requesting reservation of one or more time slots in said upstream payload channel on an upstream control channel, and (b) transmitting bitstreams from the central controller to the station indicating which slots of said upstream payload channel are assigned thereto a downstream channel, wherein said upstream control channel, said upstream payload channel and said downstream channel each have a mutually different frequency band.
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28. A circuit for enabling a station to communicate via a shared medium of a multiple access network comprising:
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(a) a receiver for receiving a plurality of bitstreams from a downstream channel, including at least one bitstream containing an indication of one or more slots of an upstream payload channel assigned to said station for transmitting bitstreams, (b) a transmitter for transmitting payload bitstreams on said upstream payload channel, only at said assigned slots of said upstream payload channel, and reservation request bitstreams containing a request to reserve one or more slots of an upstream payload channel on an upstream control channel, and (c) a first switch for coupling said transmitter to one of said payload bitstream and said reservation request bitstream, based on an upstream channel selection, wherein said upstream control channel, said upstream payload channel and said downstream channel each have a mutually different frequency band. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
a retransmission rule decision circuit for responding to said receiver receiving from said downstream channel a bitstream containing an indication that a collision occurred in said upstream control channel by causing said first transmitter to transmit said reservation request bitstream onto said upstream control channel again.
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31. The circuit of claim 28 further comprising:
a transmit scheduler for waiting until said receiver receives a bitstream from said downstream channel indicating the identity of an available group of one or more reservation slots in said upstream control channel, and if data is available for transmission from said station, randomly determining, based on said indicated available group of reservation slots, whether or not to cause said first transmitter to transmit said reservation request bitstream on said upstream control channel, but only during one of said reservation slots of said indicated group of reservation slots.
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32. The circuit of claim 28 further comprising:
retransmission rule decision circuit for setting an acknowledgment timer, after said first transmitter transmits said reservation request bitstream on said upstream control channel and, in response to said acknowledgment timer expiring before said receiver receives an bitstream containing an acknowledgment from said downstream channel, causing said first transmitter to transmit said reservation request bitstream on said upstream control channel again.
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33. The circuit of claim 32 wherein after setting said timer, but before said timer expires, said receiver receives a bitstream from said downstream channel containing an acknowledgment of receipt of said reservation request bitstream but also containing an indication that no slots in said upstream payload channel are available for allocation, and wherein, in response, said retransmission rule decision circuit refrains from causing said first transmitter to transmit said reservation request bitstream on said upstream control channel again.
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34. The circuit of claim 28 wherein said receiver receives from said downstream channel a payload bitstream containing a communicated message originating from another station in said network.
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35. The circuit of claim 28 wherein a bitstream indicating an identity of said multiple access network is transmitted on said downstream channel, wherein said identity of said network includes at least an identity of said downstream and upstream channels.
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36. The circuit of claim 28 wherein a bitstream indicating an identity of each of the assigned upstream payload slots is transmitted on said downstream channel, said bitstream indicating said identity based on at least one of a network identifier, a station identifier, an upstream payload channel identifier and a mini-slot identifier.
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37. The circuit of claim 28 wherein a bitstream indicating an identity of assigned upstream reservation request slots is transmitted on said downstream channel, said bitstream indicating said identity based on at least one of a network identifier, a station identifier, an upstream control channel identifier and a mini-slot identifier.
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38. The circuit of claim 37 wherein a bitstream indicating a notification to each station that a collision occurred at a particular reservation request slot is transmitted on said downstream channel, said bitstream indicating said notification based on at least one of said network identifier, said station identifier, said upstream control channel identifier and said mini-slot identifier.
Specification